Identity (preface.Preface_stdlib.Identity)

Identity.t is a trivial "type constructor" that allows you to lift an arbitrary value into a context. The identity can be very useful for validating implementations (by checking its laws) or for providing a fixed implementation for transformers.

Type

type 'a t

An identity is defined as type 'a t = 'a.

Implementation

The set of concrete implementations for Identity.t.

Functor

module Functor : Preface_specs.FUNCTOR with type 'a t = 'a t

Applicative

module Applicative : Preface_specs.APPLICATIVE with type 'a t = 'a t

Selective

module Selective : Preface_specs.SELECTIVE with type 'a t = 'a t

Monad

module Monad : Preface_specs.MONAD with type 'a t = 'a t

Comonad

module Comonad : Preface_specs.COMONAD with type 'a t = 'a t

Invariant Functor

module Invariant : Preface_specs.INVARIANT with type 'a t = 'a t

Additional functions

Additional functions to facilitate practical work with Identity.t.

val pure : 'a -> 'a t

Create a value from 'a to 'a Identity.t.

val extract : 'a t -> 'a

Extract the value from an Identity.t.

val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool

Equality between Identity.t.

val pp : 
  (Stdlib.Format.formatter -> 'a -> unit) ->
  Stdlib.Format.formatter ->
  'a t ->
  unit

Formatter for pretty-printing for Identity.t.